Juergen Schoenwaelder <[email protected]> writes: > On Tue, Oct 13, 2015 at 03:09:34PM +0200, Ladislav Lhotka wrote: >> >> > On 13 Oct 2015, at 13:01, Juergen Schoenwaelder >> > <[email protected]> wrote: >> > >> > On Wed, Oct 07, 2015 at 05:37:36PM +0000, Kent Watsen wrote: >> >> >> >> This is a notice to start a NETMOD WG last call for the document: >> >> >> >> Defining and Using Metadata with YANG >> >> http://tools.ietf.org/html/draft-ietf-netmod-yang-metadata-02 >> >> >> >> Please indicate your support by Thursday October 22, 2015 at 9PM EDT. >> >> We are not only interested in receiving defect reports, we are equally >> >> interested in statements of the form: >> >> >> > >> > I am concerned about this text: >> > >> > Annotations modify the schema of datastores and/or management >> > protocol messages, and may also change their semantics. Therefore, >> > due care has to be exercised when introducing annotations in >> > network management systems in order to avoid interoperability >> > problems and software failures. >> > >> > I think we should actually very clearly discourage annotations that >> > modify the schema of datastores and/or management protocol messages >> > instead of assuming all annotations are free to do so. >> >> Annotations modify the schemas by definition because otherwise XML >> attributes, and objects in JSON encoding whose names start with "@", are not >> allowed. >> > > For me, the schema of a datastore is the YANG data model. I do not > want annotations that change the YANG data model of a datastore. > Perhaps you mean something different but then the text allows multiple > interpretations and hence it is problematic.
It depends on the definition of "schema". In any case, annotations add some extra information that possibly might be persistent. FWIW, a RELAX NG schema generated for datastore + annotation is different from the one that's for datastore only. > > Annotations should add metadata but I think metadata must not change > the semantics of the data model itself. I am also concerned if > metadata changes the semantics of protocol messages. I am not Some annotations that are of this sort, such as "inactive", have already been discussed. The text you cited tries to explain possible pitfalls of such annotations, but my understanding of the consensus so far has been that it is not desirable to limit annotations to "benign" ones. I guess the considerations are similar to extensions in general: certain annotations may be a mandatory part of a protocol but is has to be said in the protocol spec. This is essentially what was done for NETCONF, and a special extension was used for defining the annotations (XML attributes). Lada > interested in standards-track mechanisms that at the end increase the > chances of interoperability problems and software failures. > > /js > > -- > Juergen Schoenwaelder Jacobs University Bremen gGmbH > Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany > Fax: +49 421 200 3103 <http://www.jacobs-university.de/> -- Ladislav Lhotka, CZ.NIC Labs PGP Key ID: E74E8C0C _______________________________________________ netmod mailing list [email protected] https://www.ietf.org/mailman/listinfo/netmod
